For the Winbond SPI flash devices. There are separate to 2 type devices. Default QE(Quad Enable) bit disabled->SG naming is W25Q128JV.Default QE(Quad Enable) bit enabled->SG naming is W25Q128JV-Q.The default Status Register-2 (Bit 2=QE bit will be 1 and can't be reset to 0). Therefore, the SR-2 will read back as 02. Please make sure your part number then choose the corresponding algorithm for programming.